Container for high pressure gas



y 1964 E. G. D. ANDREWS ETAL $132,618

CONTAINER FOR HIGH PRESSURE GAS Filed Sept. 13, 1960 FlGl.

3,132,618 CONTAINER FOR HIGH PRESSURE GAS Edward G. D. Andrews and Michael S. Hunt, Coventry,

England, assignors to Bristol Siddeley Engines Limited,

Bristol, England Filed Sept. 13, 1960, Ser. No. 55,803 Claims priority, application Great Britain Sept. 26, 1959 8 Clah'ns. (Cl. 114-20) The invention is concerned with a container for gas at a high pressure, for example 3,500 pounds per square inch. At such a high pressure the container must not be allowed to fail, as failure would be of an explosive nature. An oxygen tank in a torpedo may have an in- ,ternal'pressure of that value and if the tank should fail in a submarine, the resulting explosion wouldbe disastrous. The container must therefore satisfy the necessary strength factors; but if it is to be used in a torpedo,

it must not be so heavy that the total weight of the torpedo will exceed its buoyancy when fitted with a practice head. The present invention has an object the provision of a container which may be used for storing high pressure spaced from the outer shell by a substantially uniform diametral clearance, at least one leak path being provided from the space between the two shells and the thick- 'nesses of the two shells and' the clearance being such that, when the container does contain high pressure gas, the inner shell is stressed more highly than the outer shell and can expand into contact with the outer shell.

Preferably, the inner shell is stressed, when containing gas, at the said high pressure, to substantially 0.1% proof stress, while the outer shell has a stress below its fatigue or endurance limit. v

Where the container is of long, substantially cylindrical shape, as in a torpedo, the cylindrical wall only may be of composite structure, comprising inner and outer shells as aforesaid, the end walls each comprising a single wall of thickness sufficient to withstand the pressure of the gas with a safety factor greater than that ofthe composite cylindrical wall, both shells being attached to the end walls, so that under normal conditions the longitudinal loads are shared between the shells and, where complete failure of the inner shell has occurred, the end walls are still retained by the outer shell, the connection between theinner shell and each end wall being sealingly continuous and at least one of the connections between the 'outer shell and theend' walls providing the aforesaid leak path from the annular space between the shells.

In one form of the invention, now described by way of example with reference to the accompanying drawings, the container constitutes a tank for pressurised oxygen in a torpedo, the cylindrical wall of the tank forming a United States Patent F .part of the torpedo hull, between the head and the rear part, containing the engine, fuel tank guidance systems.

In the accompanying drawings: FIGURE 1 is a'side view of the torpedo showing the and control and Q central portion of the hull thereof, including the tank,

in axial cross-section, and

FIGURE 2 is an enlargement of part of FIGURE 1 a in the region of arrow II therein andshowing a constructional detail of the tank. The cylindrical wall of the tank is of composite strucice ture and comprises an outer shell 1 and an inner shell 2, which is thinner than the outer shell. Both shells are made of steel with an ultimate tensile strength of tons/square inch. When the container does not contain oxygen at high pressure, e.g., 3,500 pounds per square inch, the inner shell is spaced from the outer shell by a substantially uniform diametral clearance, e.g., between 0.06 and 0.08 inch, forming an annular space'3 between the two shells. The end walls 4 of the tank are of an outwardly domed shape and are of single thickness. The thickness of each of the end walls 4 is such that it has a higher factor of safety than the composite cylindrical wall. Thatis to say, if the tank should fail, the failure will occur in the cylindrical wall of the inner shell and not in the end walls.

The connections between the end wall and the inner and outer shells at each end of the tank are similar, the

shell 2 of the cylindrical wall at 5 by a circumferentially continuous weld and the outer shell 1 is extended at 6 axially beyond the position where the end wall 4 joins the inner shell 2. Acircumferentially continuous ring 7 is weldedto the extension 6 of the outer cylindrical shell at 8 by a circumferentially continuous weld. The ring 7 is in circumferential abutment with the end wall 4 at 18 and 19, the end wall 4 being urged into sealing contact with the ring 7 at these positions, by the gas pressure inside the tank. A second circumferentially continuous ring 9 is welded to the outer casing 10 of the hull of the torpedo at the adjacent end of the tank. The two rings 7 and 9 are held together by a third ring 11, which is circumferentially discontinuous and is clamped around the rings 7 and 9. The radially inner circumferential face of the ring 11 and the radially outer circumferential faces of the rings 7 and 9 have interengaging circumferentially-extending tongues and recesses, whereby the rings 7 and 9 are held from axial movement. A deformable sealing ring 12 is provided between engaging faces of the rings 7 and 9. The inner shell 2 and the end walls 4 form a completely gas-tight container, by virtue of the weld 5; but there is a leak path or paths from the space 3 between the inner and outer shells, formed by a hole 13 or holesdrilled through one or both the rings 7 and communicating at one end with the space 3 and at the other end with the remainder of the hull interior between the outside of the end-wall 4 and the outer casing 10.

In normal use, at a' pressure of, say, 3,500 pounds per square inch, the thinner inner shell expands until it comes into contact with the thicker outer shell; The stress in the inner shell is substantially equal to the 0.1% proof stress of the shell, while the stress in the outer shell is only one third of the ultimate tensile strength of the steel and is therefore well below its fatigue or endurance limit. A single cylindrical wall giving the same strength factor as a composite wall according to this invention would be thicker than the inner and outer shells together and therefore heavier.

If failure of the inner shell should occur, gas will leak into the space 3 between the inner and outer shells and the stress in the outer shell will increase, but due to the leakage path 13 provided, this increase will be temporary only, as the gas will leak away comparatively slowly into the hull so that the resulting pressure in the remainder of the hull can be kept to an acceptable value by relief valves (not shown). The thickness of the outer shell is such that it will be able to withstand this stress more than once; but preferably the tank is withdrawn from service after the failure of'the inner shell. The container according to this invention may therefore" be regarded as a fail-safe container and willnot explode on failure as would a container having a single cylindrical wall.

As the tank forms an intermediate part of the torpedo hull it is necessary to provide a connecting passage for controls connected between the rear part 14 of the torpedo and the head 15. The controls conveniently pass through a tube 16 which passes through the tank and is welded to each end wall 4. The tube therefore does not interfere with the expansion of the inner shell 2. ,"A pipe 17, passing through one of the end walls 4, conveys oxygen from the tank to an engine (not shown) in the rear part 14 of the torpedo.

As stated hereinbefore, although this container is primarily intended to be used as an oxygen tank for a torpedo, the invention may have other applications, for example, where a pressurised gas container is to be recharged several times and which may therefore tend to fail by fatigue. i

What we claim as our invention and desire to secure by Letters Patent of the United States is:

1. A container for high pressure gas, at least one of the walls of the container comprising two shells positioned one within the other, the inner shell being thinner than the outer shell and, when the container does not contain gas at high pressure, being spaced from the outer shell by a substantially uniform diametral clearance, at least one leak path being provided from the space between container is designed, the inner shell will be stressed more highly than the outer shell and will expand into contact with the outer shell, a wall at each end of the composite cylindrical wall, each said end wall comprising a single wall of thickness sufficient to withstand the pressure of the gas with a safety factor greater than that of'the composite cylindrical wall, both shells being attached to the end Walls, so that under normal conditions the longitudinal loads are shared between the shells and, where complete failure of the inner shell has occurred, the end walls are still retained by the outer shell, the connection between the inner shell and each end wall being sealingly con tinuous and at least one of the connections between the outer shell and the end walls providing the aforesaid leak path from the annular space between the shells.

6. A container as claimed in claim 5 forming a part of the hull of the torpedo intermediate its ends, the container also including a pipe passing through and sealingly connected to each end wall, the pipe providing a communication through which control connections can be passed between the forward and aft parts of the hull.

7. A torpedo having an oxygen tank comprising a cylinder wall constituting part of the hull of the torthe two shells and the thicknesses of the two shells and the clearance being such that, when the gas pressure within the inner shell is that for which the container is designed, the inner shell will be stressed more highly than the outer shell and will expand into contact with the outer shell.

2. A container as claimed in claim 1 in which the thicknesses of the inner and the outer shells are such that, when the gas pressure within the inner shell is substantially said design value, the inner shell will be stressed to substantially 0.1% proof stress and the outer shell will be stressed to a stress below its fatigue limit.

3. A container as claimed in claim 1 of substantially cylindrical shape, the cylindrical wall being of composite structure comprising inner and outer shells as aforesaid and the end walls, each comprising a single wall of thickness sufficient to Withstand the pressure of the gas with a safety factor greater than that of the composite cylindrical wall, both shells being attached to the end Walls, so that under normal conditions the longitudinal loads are shared between the shells and, where complete failure of the inner shell has occurred, the end walls are still retained by the outer shell, the connection between the inner shell and each end wall being sealingly continuous and at least one of the connections between the outer shell and the end walls providing the aforesaid leak path from the annular space between the shells.

4. A container as claimed in claim 3 in which the connection between the outer shell and the end wall at at least one end of the container comprises a circumferentially continuous ring joined to the outer shell by a circumferentially continuous weld and having a circumferentially-extendingabutment, the end wall having a similar abutment engaged by the abutment on the ring and the said ring having at least one hole therein, providing a leak' path from the annular space between the shells to the exterior of the container.

5. A container forming an oxygen tank for a torpedo and having a cylindrical wall, constituting part of the hull of the torpedo and of composite structure comprising two shells positioned one within the other, the inner shell being thinner than the outer shell and, when the container does not contain gas at high pressure, being spaced from the outer shell by a substantially uniform diametral clearance, at least one leak path being provided from the space between the two shells and the thicknesses of the two shells and the clearance being'such that, when the gas pressure within the inner shell is that for which the pedo and comprising two sheills positioned one within theother, the inner shell being thinner than the outer shell and, when the tank does not contain gas at high pressure, being spaced from the outer shell by a substantially uniform diametral clearance, at least one leak path being provided from the space between the two shells and the thicknesses of the two shells and the clearance being such that, when the gas pressure within the inner shell is that for which the tank is designed, the inner shell is stressed more highly than the outer shell and can expand into contact'with the outer shell, a wall at each end of the composite 'cylindricalwall, each said end wall comprising a single wall of thickness suflicient to withstand the pressure. of the gas with a safety factor greater than that of the composite cylindrical wall, both shells being attached to the end walls, so that under normal conditions the longitudinal loads are shared between the shells and, where complete failure of the inner shell has occurred, the end walls are still retained by the outer shell, the connection between the inner shell and each end wall beinJg sealingly continuous and at least one of the connections between the outer shell and the end walls providing the aforesaid leak path from the annular space between the shells.

8. A torpedo as claimed in claim 7 in which the tank includes at each end thereof means connecting the end wall to the adjacent ends of the inner and outer'shells of the tank and for connecting the tank to an adjacent part of the hull of the torpedo, the said means comprising a first circumferentially continuous ring, joined to the outer shell by a ciroumferentially continuous Weld and having a oircumferentially-extending abutment thereon the end wall also being joined to the inner shell by a circurnferentially continuous weld and havinga circumferentially-extending abutment thereon, the two said abutments being in engagement ,one with another, a second ciroumferentially continuous ring welded to the said adjacent part of the hull and a circumferentially discontinuous ringshaped to restrain the first and second rings from mo vemen-t axially of the torpedo, the said first ring at at least one end of the tank having at least one hole therein, providing a leak path between the annular space between the shells and the interior of the said adjacent part of the hull.

References Cited in the file of this patent UNITED STATES PATENTS 250,144- Haight Nov. 29, 1881 255,386 Hardy et al.. Mar. 21, 1882 263,407 Hicks Aug. 29, 1882 2,991,900 Poorman July 11, 1961 

5. A CONTAINER FORMING AN OXYGEN TANK FOR A TORPEDO AND HAVING A CYLINDRICAL WALL, CONSTITUTING PART OF THE HULL OF THE TORPEDO AND OF COMPOSITE STRUCTURE COMPRISING TWO SHELLS POSITIONED ONE WITHIN THE OTHER, THE INNER SHELL BEING THINNER THAN THE OUTER SHELL AND, WHEN THE CONTAINER DOES NOT CONTAIN GAS AT HIGH PRESSURE, BEING SPACED FROM THE OUTER SHELL BY A SUBSTANTIALLY UNIFORM DIAMETRAL CLEARANCE, AT LEAST ONE LEAK PATH BEING PROVIDED FROM THE SPACE BETWEEN THE TWO SHELLS AND THE THICKNESS OF THE TWO SHELLS AND THE CLEARANCE BEING SUCH THAT, WHEN THE GAS PRESSURE WITHIN THE INNER SHELL IS THAT FOR WHICH THE CONTAINER IS DESIGNED, THE INNER SHELL WILL BE STRESSED MORE HIGHLY THAN THE OUTER SHELL AND WILL EXPAND INTO CONTACT WITH THE OUTER SHELL, A WALL AT EACH END OF THE COMPOSITE CYLINDRICAL WALL, EACH SAID END WALL COMPRISING A SINGLE WALL OF THICKNESS SUFFICIENT TO WITHSTAND THE PRESSURE OF THE GAS WITH A SAFETY FACTOR GREATER THAN THAT OF THE COMPOSITE CYLINDRICAL WALL, BOTH SHELLS BEING ATTACHED TO THE END WALLS, SO THAT UNDER NORMAL CONDITIONS THE LONGITUDINAL LOADS ARE SHARED BETWEEN THE SHELLS AND, WHERE COMPLETE FAILURE OF THE INNER SHELL HAS OCCURRED, THE END WALLS ARE STILL RETAINED BY THE OUTER SHELL, THE CONNECTION BETWEEN THE INNER SHELL AND EACH END WALL BEING SEALINGLY CONTINUOUS AND AT LEAST ONE OF THE CONNECTIONS BETWEEN THE OUTER SHELL AND THE END WALLS PROVIDING THE AFORESAID LEAK PATH FROM THE ANNULAR SPACE BETWEEN THE SHELLS. 